St James’s Palace today asked British media organisations not to publish pictures of a naked Prince Harry partying in Las Vegas, despite the images being easily available online.

Royal aides confirmed the authenticity of the photographs, which depict the third in line to the throne standing in front of a topless woman, cupping his genitals with his hands. Another picture shows the Prince "bear-hugging" a naked woman from behind.

The pictures, initially published by the US celebrity website TMZ.com, were taken by a fellow reveller while the Prince was reportedly playing "strip billiards" at a party in his VIP suite at the Wynn hotel.

The tabloids were reluctant to publish the images; the nearest any of them came to doing so was The Sun asking one of its staff, Harry Miller, to bare his all in recreating a shot for its front page. Editors might once have argued that the images were already in the public domain, and their new hesitancy was attributed to the inquiry by Lord Leveson, pictured, into press practices following the phone-hacking scandal.

While St James's Palace refused to comment on the pictures, aides informed newspaper editors that the photographs were shot in circumstances where Prince Harry "had a reasonable expectation of privacy". Publication would constitute an "unjustified intrusion" into Harry's privacy, in breach of the Press Complaints Commission Editors' Code of Practice, the Palace said, despite wide availability online. Clause 3 of the code states that it is "unacceptable to photograph individuals in private places without their consent".

The royal commentator Robert Jobson asked: "Are we back to the good old, bad old days of Edward and Mrs Simpson when the whole world reported on affairs but not the UK?"